let arr = [];
let proxy = new Proxy(arr, {
  get(target,key) {
    console.log("target:", target);
    console.log("key:", key);
    return Reflect.get(target,key)
  }
  , set(target,key,value) {
    // if(key === 'length') return true;
    console.log('update', key);
    return Reflect.set(target,key,value)
  }
});
proxy.push('123');
/*
target: []
key: push
target: []
key: length
update 0
update length
*/
